The cholecystokinin (CCK)/gastrin family peptides are involved in regulation of feeding and digestion in vertebrates. In the ascidian Ciona intestinalis type A (Ciona robusta), cionin, a CCK/gastrin family peptide, has been identified. Cionin is expressed exclusively in the central nervous system (CNS). In contrast, cionin receptor expression has been detected in the CNS, digestive tract, and ovary. Although cionin has been reported to be involved in ovulation, its physiological function in the CNS remains to be investigated. To elucidate its neural function, in the present study, we analyzed the expression of cionin and cionin receptors in the CNS. Cionin was expressed mainly in neurons residing in the anterior region of the cerebral ganglion. In contrast, the gene expressin of the cionin receptor gene CioR1, was detected in the middle part of the cerebral ganglion and showed a similar expression pattern to that of VACHT, a cholinergic neuron marker gene. Moreover, CioR1 was found to be expressed in cholinergic neurons. Consequently, these results suggest that cionin interacts with cholinergic neurons as a neurotransmitter or neuromodulator via CioR1. This study provides insights into a biological role of a CCK/gastrin family peptide in the CNS of ascidians.

胆囊收缩素 (CCK)/胃泌素家族肽参与脊椎动物摄食和消化的调节。在海鞘 A 型海鞘( Cionarousta ) 中，已鉴定出海鞘蛋白 (Cionin)，一种 CCK/胃泌素家族肽。 Cionin 仅在中枢神经系统 (CNS) 中表达。相反，在中枢神经系统、消化道和卵巢中检测到了 cionin 受体表达。尽管有报道称乔宁与排卵有关，但其在中枢神经系统中的生理功能仍有待研究。为了阐明其神经功能，在本研究中，我们分析了 CNS 中 cionin 和 cionin 受体的表达。 Cionin 主要在大脑神经节前区的神经元中表达。相反，在大脑神经节中部检测到了cionin受体基因CioR1的基因表达，并且显示出与胆碱能神经元标记基因VACHT相似的表达模式。此外， CioR1被发现在胆碱能神经元中表达。因此，这些结果表明 cionin 作为神经递质或神经调节剂通过 CioR1 与胆碱能神经元相互作用。这项研究深入了解了 CCK/胃泌素家族肽在海鞘中枢神经系统中的生物学作用。